Stop TemplateView automatically passing kwargs into the context

[Alexey Boriskin]

Only TemplateView pushes self.kwargs to the context. ListView does not, I yet have to check others.
This is inconsistency and, I think, it should be fixed.

[Carl Meyer]

Setting this DDN pending comment from someone who uses class-based views. Seems like a new feature rather than a bug, in any case.

[Jonas Svensson <jonas.s.svensson@…>]

​https://github.com/django/django/pull/753

The CBV:

• BaseDetailView
• ProcessFormView
• BaseListView

Did not push the kwargs into the context

[Alexey Boriskin]

The ticket is not fixed until patch in merged into the django. Please don't set status to closed until it's not closed.

[Aymeric Augustin]

This can be backwards incompatible in keys in kwargs clash with keys in the output of get_context_data().

The current behavior might be for backwards compatibility with the now-removed function-based generic views. Maybe this was discussed on django-developers?

This would need docs (release notes + check if the CBV docs need to be updated), and tests.

[Marc Tamlyn]

I am strongly the other way on this issue - I think the feature is wrong in TemplateView and should be deprecated.

For example, it means that it's hard to have context_object_name and slug_url_kwarg the same - whether you get the object or the slug would be rather arbitrary.

[Jacob]

Agreed with mjtamlyn, so marking this wontfix.

[Marc Tamlyn]

Jacob - what's your opinion on taking the deprecation the other way - this one-off behaviour of TemplateView has bitten me before. Personally I'd like the views to be consistently *without* this feature.

[Aymeric Augustin]

IIRC TemplateView works like this for backwards-compatibility with the (now defunct) function-based generic views.

It would make sense to normalize it now, assuming we can figure out a deprecation path.

[Marc Tamlyn]

Hmm, I know I'd done something at some point using these views which had bitten me, but I can't remember what it was. This is near impossible to deprecate nicely and probably shouldn't be that big a deal.

That said, it didn't exist before 1.5 in its current form - the way these arguments are used was (backwardsly incompatibly) changed then anyway. Personally I'd like to just remove it as it "feels wrong", but whether that is a good idea is another question.

History lesson

Django 1.2 had direct_to_template which would pass through URL kwargs as an object called params into the context
Django 1.3 & 1.4 continued this pattern in the new TemplateView
Django 1.5 changed TemplateView to place the arguments directly into the context (and deprecated direct_to_template)

My personal feeling is that using URLconf kwargs directly in a view is a bad pattern, but it is a historical Django pattern. This, and the ability to customise CBVs using the as_view() call, are the remaining parts of it.

[loic84]

I ran into the same problem as @mjtamlyn with TemplateView; and I also think that having the URL kwargs directly in the context_data is an anti pattern.

The anti pattern added to the discrepancy between the different views is IMO a problem big enough to warrant a documented backward incompatible change.

I tried to think of a transparent deprecation cycle, but what I found was at best fragile and hackish.

One option would be to ask people to set a kwargs_to_context = False argument on their TemplatView to get the "new" behavior and therefore opt out from the DeprecationWarning.

Thoughts?

[Tim Graham]

I'm not much of a user of CBVs but that deprecation plan sounds like it would work.

[Chris Jerdonek]

Note that there is a distinction between passing **kwargs to get_context_data() and having get_context_data() return **kwargs.

Personally, I would favor TemplateView continuing to pass **kwargs to get_context_data() even if its return value is changed by default not to include kwargs. This would keep overriding get_context_data() simple because you can simply access **kwargs in the method without having to decide between **kwargs and self.kwargs.

For consistency, I would like it if all generic views passed the full view's keyword arguments to get_context_data(). Some classes like ProcessFormView restrict what is passed to get_context_data(), which was surprising to me because then **kwargs for the method differs from self.kwargs. I just opened #21964 which is about this issue.

[Mariusz Felisiak <felisiak.mariusz@…>]

In 4ed53475:

Fixed #19878 -- Deprecated TemplateView passing URL kwargs into context.

[Mariusz Felisiak <felisiak.mariusz@…>]

In bb8f6693:

Fixed #31877 -- Reverted "Fixed #19878 -- Deprecated TemplateView passing URL kwargs into context."

This reverts commit 4ed534758cb6a11df9f49baddecca5a6cdda9311.

[Mariusz Felisiak <felisiak.mariusz@…>]

In e81aa7a:

[3.1.x] Fixed #31877 -- Reverted "Fixed #19878 -- Deprecated TemplateView passing URL kwargs into context."

This reverts commit 4ed534758cb6a11df9f49baddecca5a6cdda9311.

Backport of bb8f66934d93faf80cd1a2dda65aaedce21a6fc5 from master

[Mariusz Felisiak]

Marked as wontfix because we don't have a clear deprecation path (see #31877).